[PATCH] HTTP/2: add fast-path for HTTP/2 requests without request body

[Piotr Sikora]

Hey Valentin,

> That doesn't look like a correct patch to me as it changes behavior
> of ngx_http_read_client_request_body() specifically for HTTP/2 case.

Well, the behavior is already different, which is what this patch is
trying to mitigate.

In case of HTTP/1.x, a single buffer with headers is produced.

In case of HTTP/2, two buffers are produced: one with headers and one
empty with last_buf = 1.

> Note, that in case of HTTP/1.x it always allocates r->request_body
> for the main request unless r->discard_body is set.
>
> Even if it doesn't break something in nginx at the first glance,
> there's always a chance that some 3rd-party modules can depend
> on this.
>
> Anyway, this change should be made either for both protocols or
> for none of them.

Fair enough, I'll update patch to always allocate r->request_body.

Best regards,
Piotr Sikora